While watching any sporting event, including the Super Bowl, I always like to be dressed the part- especially if my team is playing.
One place where I buy my team's clothes is at Dick's Sporting Goods. Dick's has a nice selection of different styles and materials. Beware though, if your team is not the home team or state team, it is harder to find the clothes and gear you are looking for.
One thing I really like about Dick's is that they have a rewards program. You get points everytime you shop at Dicks. And once you get a certain amount of points, you get gift certificates. Also, by joining the rewards network, you get coupons sent in the mail.